Process of manufacturing chemical picture carriers



June 14,1938. RENCK Er-AL 2,120,416

PROCESS OF MANUFACTURING CHEM I CAL PICTURE CARRIERS Filed May a, 1935 41M -r Mm M M 4M Patented June 14, 1938 PATENT OFFICE PROCESS OF MANUFAUIURING CHEMICAL PICTURE CARRIERS Carl Renck and Hans Hermann Heinrich Renck, Hamburg, Germany Application May 8, 1935, Serial No. 20,418

In Germany May 18, 1934 3 Claims.

This invention relates to a process-of manufacturing chemical picture carriers. It has been found that an absolutely solid, ink repelling amalgam layer can be formed on the surface of the a printing plates when the plates, besides being treated for example with mercury salts dissolved in Water, are also subjected to a treatment with metal salts, particularly silver nitrate or copper sulphate dissolved in water. If for example a 10 sheet iron coated with brass is treated with mercury nitrate and the plate thus treated is dipped in a silver nitrate solution, asolid amalgam layer is produced which has anink repelling property and in which above all a displacement of the 15 mercury is impossible. Practical experiments have shown, that the solutions can also be employed as a mixture. As regards the mutual proportions of the mixture it may be said that only as much mercury should be present in the solu- 20 tion asis necessary for preserving an ink repellent property, and the silver or metal salts must be added in such quantities that the ink repellent effect caused by the mercury is just maintained.

In any case under these conditions a hard amal- 25 gam layer is formed, and it is not possible to squeeze the mercury out of this layer even under heavy pressure.

The process for printing with printing plates having asolid amalgam surface consists in treat- 30 ing the'plates, for example sheet iron plates coated with brass and on which the picture is copied by copying or by offset printing, with mercury salts dissolved in water and with salts of other metals capable of amalgamation dissolved in water. The 35 steps of tlns treatment may be carried out successively or in a combined'bath.- Consequently,

the plates are, for example dipped first in a solution of mercury nitrate and then in a silver nitrate solution. The plates are then clamped on 40 the impression cylinder "a. b is an inking roller of the inking mechanism situated below the platen cylinder, c the mercury feed-roller which is permanently in touch with metallic mercury 11 and finally e is the intermediate roller which is 45 alternatelybrought into contact with the mercury feed roller c and the inking roller b by an eccentric driven by the machine but not shown in the drawing, In the position illustrated the intermediate roller e is rotated very slowly by the. 50 roller and pulls oil the roller c strips of thin mercury film about 1 cm. in width. It then comes into contact-with the inking roller b with which it rotates quickly corresponding to the number of revolutions of the cylinder. Thus, the it mercury on the roller b is well rubbed and a perfeet embedding of the mercury in very finely distributed state is effected by the roller b in the hard amalgam layer on the printing plate. The amalgam surface of the plate readily takes up this very finely distributed mercury in the man- 5 ner described, remains solid and ensures perfect printing for any number of copies.

Furthermore the amalgam layer on the printing plates may be built up to any desired thickness. The result is, that the building up can be so high that the portions of the picture to be printed become gradually deeper and finally disappear entirely. However, the deeper they lie, the less they come into question for the reproduction, that is the lighter will be thetotal tone of the print. It is therefore possible, according to the invention, to vary the color toning by the height of the built up amalgam layer. Moreover, a mixed bath may be prepared according to the proportion of the .mercury and metal salts, in order to always obtain the same toning of the prints just as desired. The building up of the amalgam layer can evidently be carried out in places by means of a brush or the like.

The process is therefore very simple in that the picture is for example copied or printed on to a tinned sheet iron plate with brass on its surface. The plate is then dipped into a 1% mercury nitrate solution. A mercury-brass amalgam forms on the portions .not covered by the picture, and this amalgam is fixed by dipping into a silver nitrate solution of about 0.5%. By repeated, alternate dipping into the baths the salts on the printing plate can be built up to a certain height to ensure a certain color tone value of the prints. This is particularly important in view of the different kinds of paper, in order to always obtain very sharp pictures and a contrast effect.

We claim: e

1. A process of manufacturing chemical picture carriers, consisting in providing aniron base plate with a covering of brass, applying the picture onto said covering, covering the portions of the covering not covered with the picture with an aqueous solution of a mercury salt and of a silver salt-and continuing this treatment until these treated portions of said brass covering project above the picture.

2. A process of manufacturing chemical picture carriers, consisting in providing an iron base plate with a covering of brass, applying the pic ture onto said covering, covering the portions of the covering not covered with the picture with an aqueous solution of a mercury salt and thereafter withan aqueous solution of a silver salt and with a covering of brass, applying the picture onto said covering, covering the portions of the covering not covered with the picture with an aqueous solution of mercury nitrate, then with an aqueous solution of silver nitrate and in continuing first the one treatment and then the other until these treated portions of said brass covering project above the picture.

CARL RENCK. I 4 HANS HERMANN HEINRICH RENCK. 

